Method of operating a wind power station

ABSTRACT

When planning and setting up wind power installations, the visual detractions to be expected on the part of the wind power installation on the environment play an increasingly important part in approval and acceptance. The shadow casting caused by the wind power installation on the adjoining properties is often perceived by the residents as being very troublesome. A wind power installation is provided by means of which shadow casting regulation is improved. That is achieved by a method of operating a wind power installation wherein a first light intensity is detected in a region of direct light irradiation and a second light intensity is detected in a shadowed region, and wherein the wind power installation is shut down if the difference between the first light intensity and the second light intensity is greater than a predetermined value.

TECHNICAL FIELD

The present disclosure generally relates to wind power installations andmethods for operating wind power installations.

BACKGROUND INFORMATION

When planning and setting up wind power installations, the visualdetractions to be expected on the part of the wind power installation onthe environment play an increasingly important part in approval andacceptance. If for example a wind power installation is placed in theproximity of a residence, it is possible, when the sun is in unfavorablepositions, that the wind power installation or the rotor thereof isbetween the sun and the residence. If the sunshine is not affected bycloud, the rotating rotor constantly throws a (strobing) shadow on tothe property. The shadow casting caused by the wind power installationon the adjoining properties is often perceived by the residents as beingvery troublesome. Even if the wind power installation satisfies thelegal approval requirements there is however not always any guaranteethat the undesired shadow casting effect is prevented.

DE 199 29 970 A1 discloses a shadow casting regulating system in whichthe intensity of light is detected in order to derive therefrom whethera shadow can occur at all.

It will be noted however that an adequate level of light intensity isonly one of the prerequisites for a shadow to occur. A furtherprerequisite is for example clear air. Under hazy visual conditions, thelight is diffused so that only slight or no shadowing occurs, in spiteof the high level of light intensity. Control of a wind powerinstallation, which is based on the intensity of the light, can resultin a shutdown although there is no shadow.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to provide a wind powerinstallation, by means of which that disadvantage is overcome.

According to the invention that object is attained by a method ofoperating a wind power installation as set forth in herein. Advantageousdevelopments are described herein.

The invention is based on the realization that shadow casting can occuronly at a given position of the sun and with given light conditions orcloud cover if there is direct solar irradiation with a high level oflight intensity. As however the cloud cover cannot be detected directly,but nonetheless can result in diffuse light in which no significantshadow occurs, a difference in brightness between light and shadow,which can be easily detected, is used. If the difference stays below apredetermined value, accordingly no clearly perceptible shadow occursand therefore there is no need for the wind power installation to beshut down.

On the other hand, a disturbing shadow can occur even with acomparatively low level of light intensity. That can again be easilyascertained by detecting the difference in brightness between light andshadow.

As is known, the position of the sun is dependent on the time of theyear and the time of day and can be ascertained by means of measurementor calculation programs for any relevant immission point (that is thelocation [region] at which shadow casting can occur). The basis forshadow-based shutdown of a wind power installation is accordingly thecalculated times in which shadow casting can occur in respect of aneighboring resident (at the immission point) because of the position ofthe sun and the geographical arrangement of the installation. Inparallel with the predetermined times in respect of the position of thesun, the difference between light and shadow is ascertained by way oflight sensors and thus the plausibility of shadow casting occurring ischecked. It is only if a shadow occurs during the predetermined times inrespect of the position of the sun, at which a shadow can be cast at theimmission point, that shadow-based shutdown of the wind powerinstallation occurs.

In the case of the wind power installation according to the invention,shadow-based shutdown can be implemented by way of an input/displaydevice (LC display). For that purpose the settings or values of thecurrent levels of light intensity and the shutdown difference betweenlight and shadow can be read off. In addition, it is possible to seefrom the display the status that the shutdown has at the current time,that is to say whether it is switched on or off or is active orinactive. Input of the shutdown times can be predetermined or loaded, ina separate menu.

In the mode ‘shadow-based shutdown’, the parameters current first lightintensity (with direct light incidence) (value in %), current secondlight intensity (in a shadowed region) (value in %), shutdown difference(value in %), shadow shutdown (on/off) or shadow shutdown(active/inactive) are displayed. In that respect the shutdown differenceis a value of the difference between the first light intensity (directlight irradiation) and the second light intensity (shadowed) at whichthe wind power installation is to be shut down. If for example a windpower installation is very close to an immission point, the shadow whichis cast can be disturbing even when the sky is slightly overcast.Therefore in that case (the wind power installation is very close to theimmission point in question), the installation should receive a lowervalue for the shutdown difference, than for the situation where theimmission point is further away from the wind power installation. Inregard to the levels of light intensity, a low percentage valuesignifies a low level of light intensity (for example when the sky isovercast) and a high percentage value signifies a strong lightintensity, for example direct sun irradiation, which indicates that thesolar irradiation is not disturbed by cloud cover or mist. Shadowshutdown (on/off) indicates whether that is at all activated. Shadowshutdown (active/inactive) specifies whether the installation isshutdown at present because of a shadow being cast.

If, for the difference, a value above the shutdown difference isascertained and if at the same time there is coincidence in the inputtedtime window, which takes account of the solar irradiation or theposition of the sun, the wind power installation stops automatically ifshadow-based shutdown is switched to ‘on’. While the installation isstopped because of a shadow being cast, a corresponding status messageappears in the main menu of the display device.

The value of the shutdown difference can be altered by way of suitableinputs. As the shadow of the rotor blades becomes weaker with increasingdistance in relation to the immission point and at some point losessignificance entirely, the cast shadow still has an unfavorable effectwith increasing distance only when a greater difference is involved. Theshutdown difference must be set in accordance with local factors becausethe shutdown difference also depends on the geographical factors on thespot.

The light conditions are also continually further measured after theinstallation stops. The wind power installation automatically startsagain if the shutdown difference falls below its specified value for aduration of more than 2 minutes, preferably 10 minutes, or the shadowhas moved (by virtue of a change in the position of the sun or becauseof the sun's path), to such an extent that there are no longer anyadverse effects due to shadow casting at the immission point.

The times for the occurrence of shadow casting are edited for input byway of a menu. In that respect the values are composed of a beginningand an end date and a start and a stop time. Inputted values can bealtered, expanded or erased at any time, which can be effected by meansof manual input or by reading in a suitable program.

The times in respect of the position of the sun are inputted in theformat of Winter time. Leap years are also taken into account in theprogramming.

The times for shadow-based shutdown can always be called up at thecurrent time or afterwards by way of remote monitoring so that it ispossible to provide proof in regard to compliance.

A wind power installation for carrying out the foregoing method includesa data processing apparatus in which the positions of the sun or datarepresenting same are stored. The wind power installation furtherincludes a plurality of and preferably three light sensors. Thosesensors are arranged in uniformly spaced relationship around theinstallation.

With three sensors, there is thus a spacing of 120° between therespective sensors if they are arranged on a notional circle around thewind power installation. When using three sensors, one is alwayssubjected to direct light incidence and at least one further sensor isarranged in a shadowed region. It is therefore always possible toascertain the difference in light intensity.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention is described in greater detail hereinafter by means of anembodiment by way of example.

FIG. 1 shows a side view of a wind power installation according to theinvention,

FIG. 2 shows a simplified plan view on to a cross-section through thepylon above the light sensors,

FIG. 3 shows a side view illustrating the shadow casting effect at twodifferent positions of the sun, and

FIG. 4 shows a plan view of the shadow casting effect also at twodifferent positions of the sun.

DETAILED DESCRIPTION

FIG. 1 shows a simplified side view of a wind power installation 1.

That wind power installation 1 includes a pylon 10, at the head of whichis arranged a pod 12 with rotor blades 14. Arranged at a predeterminedheight on the pylon 10 are sensors 16 which detect the light intensity.Arranging the sensors 16 at a predetermined height substantiallyprevents them from being the subject of malicious damage ormanipulation.

In that respect the height can be so selected that the sensors 16 can bereached at reasonable cost in order for example to be able to clean themor also replace them. It will be appreciated that it is also possible toprovide heating for the sensors 16 in order to prevent or eliminateicing thereof.

As an alternative to mounting the sensors 16 on the pylon 10 of the windpower installation 1, it will be appreciated that the sensors 16 canalso be mounted on separate masts (not shown) or other suitable devices.

FIG. 2 is a simplified view in cross-section through the pylon 10 of thewind power installation 1 above the sensors 16. It can be seen from thisFIG. 2 that in this case three sensors 16 are preferably disposed atuniform spacings at the outer periphery of the pylon 10. The spacingbetween the sensors is therefore 120°.

By virtue of the round cross-section of the pylon 10, one half of theperipheral surface of the pylon 10, that is to say a region of 180°, isalways exposed to the direct incidence of light. Accordingly the otherhalf of the peripheral surface (again 180°) will be in shadow. The useof at least three sensors therefore means that at least one is certainto be exposed to direct incidence of light and at least one is inshadow.

Accordingly, at any desired moment in time, the light intensity whendirect light irradiation is involved and the light intensity in shadowcan be detected, and the difference thereof can be ascertained. Thatdifference can be determined by the control system of the installationand used straightaway for control according to the invention of the windpower installation.

FIG. 3 shows a wind power installation, for example of type E-40 fromEnercon, which is at a given distance E from a house 2. That house 2 canalso be referred to as the immission point A.

When the sun rises in the morning and also throughout the day in theWinter time, the sun only rises to a low height—always as viewed fromthe immission point A—so that when the sun is in position I the angle ofincidence is βI.

If the sun rises higher—position II of the sun—that involves a differentangle of incidence βII of the rays of the sun. Those angles of incidenceβI and βII (it is possible to envisage any other angles of incidence) ofthe rays of the sun also establish when in general a shadow can be castdirectly at the immission point A.

The scenario illustrated in FIG. 3 is shown once again in FIG. 4, fromanother perspective. When the sun is in the south east (once againconsidered from the immission point), the rays of the sun impinge on thewind power installation at an angle βI—in relation to the west-eastaxis—.

As soon as the sun has traveled further in the direction of south, therays of the sun are incident on the wind power installation 1 at anotherangle βII.

It is only when the position of the sun which is a function of thegeographical location on the Earth and the angles of incidence α and βprovides that the shadow of the wind power installation is incident onthe immission point A, that the wind power installation is shut down ifthe difference between light and shadow is above a predetermined value,namely the shutdown difference. The shutdown difference depends not onlyon the light incidence but also the distance in relation to theimmission point. If a wind power installation is very close to theimmission point in question, the cast shadow which occurs can betroublesome even with a slightly overcast sky. In such a situationtherefore the wind power installation should acquire a lower value forthe shutdown difference than for the situation where the immission pointis further away from the wind power installation.

If the difference is below the shutdown difference, the wind powerinstallation—irrespective of the position of the sun—is not shut downand can still generate electrical energy. Such a situation occurs inparticular when the sky is heavily clouded.

The further away that a wind power installation is from the immissionpoint, the correspondingly shorter are the times within which in generala shadow casting effect can occur at the immission point.

The difference can be measured directly at the immission point A or atthe wind power installation. As the immission point and the wind powerinstallation are relatively close together, the light intensity valuesmeasured at the wind power installation are also valid for the immissionpoint A.

The difference itself can be measured for example with a plurality oflight sensors whose values are processed by a data processing apparatusassociated with the wind power installation. The positions of the sun atwhich shadow casting can occur at the immission point are alsoprogrammed in that data processing apparatus. It will be easilyappreciated that those ‘shadow-casting’ positions of the sun aredifferent for each wind power installation and therefore the dataprocessing apparatus has stored, for each wind power installation, adifferent position of the sun at which a shadow can be cast.

It will be appreciated that it is also possible that, in the case of awind farm arranged in the proximity of an immission point, where ashadow casting effect is to be avoided, this can be controlled by acentral data processing apparatus which switches off a respectiveindividual wind power installation of a wind farm when that installationcauses a shadow to be cast at the immission point.

If a shadow is cast, the wind power installation is not shut downimmediately but only when the shadow has been cast over a certain periodof time, for example between 5 and 10 minutes.

If a shadow is no longer being cast, for example because clouds havecome between the sun and the wind power installation, it is alsopossible to provide that the system does not switch on the wind powerinstallation again immediately, but waits for a certain time, forexample between 5 and 10 minutes, and provides for switching on the windpower installation and for causing it to run again, only when thedifference was below the shutdown difference within that period of time.

It is also possible to program further positions of the sun for the windpower installation if that is necessary, besides shutdown positions ofthe sun which have already been programmed.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary, to employ techniques andstructures of the various patents, applications and publications toprovide yet further embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the invention to thespecific embodiments disclosed in the specification and the claims.Accordingly, the invention is not limited by the disclosure, but insteadits scope is to be determined entirely by the following claims, whichare to be construed in accordance with established doctrines of patentclaim interpretation.

1. A method of operating a wind power installation, the methodcomprising: detecting a first light intensity in a region of directlight irradiation; detecting a second light intensity in a shadowedregion; and shutting down the wind power installation if a differencebetween the first light intensity and the second light intensity isgreater than a predetermined value.
 2. A method according to claim 1wherein shutting down the wind power installation includes shutting downthe wind power installation only at a predetermined position of a sun.3. A method according to claim 2 wherein the wind power installation isat least temporarily shut down at a predetermined position of the sun.4. A method according to claim 2 wherein predetermined positions of thesun at which shutdown of the wind power installation can be triggeredare stored in the wind power installation or at a control and/or dataprocessing apparatus associated with the wind power installation.
 5. Amethod according to claim 1, further comprising: determining thedifference between light and shadow using a plurality of light sensors;and effecting an evaluation from the determined difference using a dataprocessing program.
 6. A wind power installation, comprising: firstmeans for detecting light intensity in a first region; second means fordetecting light intensity in a second region that is less illuminatedrelative to the first region; and a data processing apparatus whichcontrols the wind power installation and in which are stored positionsof a sun or values representative thereof, wherein shutdown of the windpower installation can take place based at least in part on a comparisonbetween the detected light intensities and the stored positions of thesun or values representative thereof.
 7. A wind power installationaccording to claim 6 wherein the wind power installation is coupled to aplurality of light sensors that comprise the first and second means, bymeans of which respectively current intensity of light and shadow orintensity of light and shadow ascertained over a certain time ismeasured, and wherein data determined by the light sensors are processedby the data processing apparatus and shutdown of the wind powerinstallation is effected if a difference between light and shadow isabove a value if a position of the sun is assumed.
 8. A wind powerinstallation according to claim 7 wherein at least three substantiallyuniformly spaced sensors are arranged around the wind powerinstallation.
 9. A wind power installation according to claim 6, furthercomprising a display device, to reproduce a status of shadow-basedshutdown.
 10. A wind power installation according to claim 6 whereinbeyond the stored positions of the sun, fresh positions of the sun forfurther immission points can be stored, which is effected byprogramming.
 11. A wind farm having a plurality of wind powerinstallations according to claim
 6. 12. A wind power installationcomprising a data processing apparatus which controls the wind powerinstallation and in which are stored the positions of the sun or valuesrepresentative in that respect, in respect of which shutdown of theinstallation can take place, characterised in that the wind powerinstallation is coupled to at least three light sensors which arearranged uniformly spaced around the wind power installation and bymeans of which the respectively current intensity of light and shadow orthe intensity of light and shadow ascertained over a certain time ismeasured, and that the data determined by the light sensors areprocessed by the data processing apparatus and shutdown of the windpower installation is effected if the difference between light andshadow is above a predetermined value when a predetermined position ofthe sun is assumed.
 13. A wind power system, comprising: a firstdetector to detect a first light intensity in a first region; a seconddetector to detect a second light intensity in a second region, thesecond light intensity being a lower light intensity relative to thefirst light intensity; and a control system to disable at least aportion of the wind power system if a difference between the first lightintensity and the second light intensity is greater than a value. 14.The wind power system of claim 13 wherein the first and second detectorscomprise part of a plurality of substantially uniformly spaced detectorsto detect light intensity at different regions.
 15. The wind powersystem of claim 13 wherein the control system can disable the portion ofthe wind power system based on a comparison of a value associated withthe detected first and second light intensities with stored valuesassociated with a position of a sun.
 16. The wind power system of claim15 wherein the control system can use software to perform the comparisonof the value associated with the detected first and second lightintensities with stored values associated with the position of the sun.